I. Прочитайте следующие слова и определите, к какой части речи они относятся. Переведите их на русский язык.
Type, early, machinery, cylindrical, proper, entire, wrap, insert, unit, adjacent, divert, path, equal, reason, case, simplify, below, regardless, number, drawing.
II. Найдите в тексте эквиваленты следующих слов и словосочетаний:
катушки нужной формы, соседний коллектор, обмотка якоря, конечная э. д. с., равный, в этом случае, упрощенная схема.
III. Заполните пропуски, выбрав нужный вариант.
1. Brushes having the ... polarity were connected together (different, same). 2. The ... of parallel paths through a lap winding was equal to the ... of poles (number, type). 3. The wave winding was used for ... applications (high-current, high-voltage). 4. The winding passes under every pole before it ... to the pole from which it started (comes back, uses). 5. The entire coil is inserted into the armature ... (winding, slots). 6. The e.m.f. ... in a wave winding is equal to that induced in one-half of the total number of armature conductors (developed, used).
IV. Переведите предложения на русский язык, определите тип придаточного предложения.
1. The way in which the coils in the lap winding are connected can be seen in the diagram. 2. There are two points where the e.m.f.'s in adjacent conductors are meeting. 3. If brushes are placed at these points, current will flow from the armature winding at A and B and into the winding at B and D. 4. The winding passes under every pole before it comes back to the pole from which it started. 5. Below you will see that in this case the winding is divided into only two parallel paths.
V. Выразите согласие или несогласие, употребив выражения: Yes, it is right; No, it is not right; No, it is wrong (парная работа).
1. The ring type armature is often used today. 2. The number of parallel paths through a lap winding is equal to the number of poles. 3. The current delivered to the external circuit is equal to the sum of the currents in each of the parallel paths (in the lap winding). 4. Brushes having different polarity can be connected together. 5. In a lap winding the two ends of each coil are connected to adjacent armature segments. 6. Wave winding has many parallel current paths.
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VI. Переведите на английский язык слова второго собеседника в диалоге.
1. What types of armatures do you know?
2. Есть два типа якорей, применяемых в генераторах постоянного тока, – барабанный и кольцевой.
1. Is the ring type armature widely used today?
2. Насколько я знаю, этот тип применялся в ранних конструкциях вращающихся машин, но редко применяется сейчас.
1. And what type of armature is the standard armature construction today?
2. Это барабанный якорь.
1. What types of drum type armature winding do you know?
2. Они могут быть двух видов – петлевая и волновая обмотки.
1. What applications are lap and wave winding used for?
2. Петлевая обмотка применяется при большой величине тока, а волновая обмотка там, где высокое напряжение.
VII. Расскажите, употребив данные слова и словосочетания, о двух видах обмотки барабанного якоря:
1) петлевой обмотке – windings, drum type armatures, lap-winding, the number of parallel paths (poles), the current of the external circuit, the sum of the currents, high-current applications, are, is equal to, is used for.
2) волновой обмотке – (wave) winding, connections, under every pole, before, only two parallel current paths, only two brushes, regardless of, number of poles, high-voltage application, are made so, that, passes, comes back to, started, has, can use, is used for.
Text 7
Types of D.C. Generators
Most practical d.c. generators have electromagnetic fields. Permanent-magnet fields are used only in very small generators called "magnetos"; so that, to produce a constant field for use in a generator, the field coils must be connected across a d.c. voltage source. The d.c. current in the field coils is called the "excitation current", and may be supplied either from a separate d.c. voltage source, or by using the d.c. output of the generator itself.
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If the field is supplied with current from an external source, the generator is said to be "separately-excited"; but if some of the generator output is used to supply the field current, it is said to be "self-excited". In a self-excited generator the field coils may be connected either in series with the armature coils ("series"), in parallel with the armature coils ("shunt"), or partly in series and partly in parallel with the armature coils ("compound").
Separately-excited d.c. generators have two circuits: the field circuit, consisting of the field coils connected across a separate d.c. source, and the armature circuit, consisting of the armature coil and the load resistance.
In a separately-excited d.c. generator, the field is independent of the armature, since it is supplied with current from either another generator (exciter), an amplifier or a battery. The separately-excited field provides a means of controlling the power output of the generator. With a slight change in the field current, a large change in the load current will result.
The separately-excited generator is frequently used in automatic motor control systems. In these systems the field current is controlled by an amplifier, and the output of the generator supplies the current which drives a motor.
Words and Word Combinations
| magneto n | магнето |
| field coil | катушка возбуждения, катушка индуктора |
| excitation current | ток возбуждения |
| separate a | отдельный |
| separately-excited generator | генератор независимого возбуждения |
| self-excited generator | генератор с самовозбуждением |
| output n | мощность |
| some | зд. часть |
| field current | ток возбуждения, ток намагничивания |
| partly adv | частично |
| compound a | смешанный |
| independent of a | независимый от |
| exciter n | возбудитель |
| provide v | обеспечивать |
| a means n | средство |
| power output | мощность на выходе, выходная мощность |
| slight a | маленький, незначительный |
| result v | происходить |
| drive v | приводить в движение |
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Е x e r c i s e s
I. Прочитайте слова и определите, к какой части речи они относятся. Переведите их на русский язык :
practical, voltage, source, separate, supply (supplied), slight, frequency, amplifier, external, separately, excite (excited), exciter, excitation, a means.
II. Дайте эквиваленты следующих слов и словосочетаний :
внешний источник, соединенный последовательно (параллельно), возбудитель, средство, незначительное (небольшое) изменение, часто, возбуждение, генератор с самовозбуждением.
III. Выберите нужный предлог : with , of, in, by, from.
1. The field was supplied ... current ... an external source. 2. ... a separately-excited d.c. generator, the field is independent ... the armature. 3. ... a slight change ... the field current, a large change ... load current resulted. 4. ... automatic motor control systems the field current is controlled ... an amplifier. 5. Permanent-magnet fields are used only ... very small generators.
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